Scattered laser radiation and broadband actinic ultraviolet plasma emissions during LADARVision excimer refractive surgery

PURPOSE: To evaluate the potential occupational health hazards associated with scattered actinic ultraviolet (UV) laser radiation and broadband actinic UV plasma emissions during refractive surgery. SETTING: Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, D.C., USA. METHODS: Intraoperative radiometric measurements were made with the Ophir Power/Energy Meter (LaserStar Model with silicon detector, Model PD-10) and the International Light Radiometer/Photometer (Model IL 1400 with actinic ultraviolet detector, Model SEL240) with and without UV blocking filters (BLK 270 and Schott types WG-280 and WG-230). Measurements made during laser calibration as well as laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) procedures were evaluated using a worst-case scenario and then compared with the American Conference of Governmental Industrial Hygeinists (ACGIH) Threshold Value Limits (TLV) to perform a risk/hazard analysis. RESULTS: Most optical emissions were between 193 nm and 280 nm, and approximately 25% of the measurement result was due to broadband emissions greater than 270 nm for calibration targets. About 25% of optical emissions during LASIK were beyond 230 nm. No emissions beyond 230 nm were observed during PRK. Ultraviolet scattered radiation level was similar between PRK and LASIK. Maximum measured values of 80 nJ/pulse at 14 cm for PRK and 45 nJ/pulse at 38 cm for LASIK were used as the absolute worst-case analysis for exposure. Assuming the worst-case exposure conditions are equal to the maximum measured value during these studies at a workload of 20 patients per day, the cumulative occupational exposure at close range of actinic UV radiation did not exceed the 8-hour occupational exposure limit of 3 mJ/cm ² for any 24-hour period. CONCLUSIONS: Scattered UV laser radiation did not exceed occupational exposure limits at distances greater than 30 cm from either laser calibration targets or patient treatments over a workday. Laser eye protection is not necessary to protect operating room personnel since exposure levels are very low even under a worst-case scenario.